Abstract: A laser system includes a multimode fiber (MMF) receiving a single-mode input beam and a mechanical oscillator coupled to the MMF. The oscillator is operative to modulate a phase of interference wave by periodically extending the fiber total length at such a frequency that a cross-coupling coefficient between fundamental and at least one high-order modes is substantially minimized.

Abstract: A method of thermally treating a surface of workpiece includes training a laser beam upon the surface and supplying a gaseous mixture to the surface. The mixture is configured with a process gas and at least one heat generating gas capable of having its molecules dissociate while generating an additional thermal energy which substantially raises the temperature of the surface.

Abstract: A laser system includes a multimode fiber (MMF) having a permanent perturbation region which is provided at the predetermined distance from the upstream end of the MMF. The perturbation region is configured so that propagating fundamental and at least one high-order mode (HOM) originated upstream from the perturbation region are split into multiple HOMs which are substantially in counterphase. Hence, the HOMs destructively interfere with and substantially cancel one another.

Abstract: A two-way optical amplifier system amplifies upstream and downstream optical signals in a passive optical network (PON). The downstream optical amplifier system includes an optical amplifier (EDFA), configured and arrange to amplify the downstream optical transport signal.

Abstract: A powerful fiber laser system is configured with at least one gain block. The gain block includes an input fiber guiding a pump light, a multiclad active fiber receiving the pump light so that a major portion is absorbed in the core of the active fiber while a minor portion of the pump light propagates in the inner cladding of the active fiber, and a multiclad output fiber. The multiclad output fiber is configured with a core, guiding a signal lased by the core of the active fiber upon absorption of the major portion of the pump light, an inner cladding receiving the minor portion of the pump light and an outer cladding. The inner and outer claddings of the multiclad output fiber have respective refractive indexes which are selected so that the refractive index of the outer cladding is higher than that one of the inner cladding.

Abstract: A high power pulsed laser system is configured with at least two gain blocks and with at least one saturable absorber (SA) coupled to the output and input of the respective gain blocks. The SA is configured so that Qsat_sa<Qsat_gb, wherein Qsat_sa is a saturation energy of the SA, and Qsat_gb is a saturation energy of the gain blocks. The SA is further configured with a recovery time ?<1/f providing for the substantially closed state of the SA, wherein the f is a pulse repetition rate, and with the recovery time ? smaller than a round trip time Tround_trip=2*(L1+L2)*n/c, where L1, L2—lengths of the respective gains gain blocks, n—a refractive index of active media, c—a speed of light in vacuum.

Abstract: A control circuit for a fiber amplifier having a first stage pump and at least one second stage pump and method of controlling thereof is disclosed. The control circuit includes a control gate controlling a current through the first stage pump. A sensor for detecting a voltage across the first stage pump and providing a measured output of the voltage is provided. The control circuit further includes a control loop configured for selectively controlling the current through the control gate in accordance with the measured output and a set reference point is also provided.

Abstract: A powerful high-brightness laser pump modules is configured with a plurality of spaced laser diodes each generating a light beam at a pump wavelength, and respective groups of optical components guiding the light beams along parallel light paths. The groups of the optical components each include a lens assembly and a bending mirror configured to couple the beam light into an output fiber which is common to all groups of the optical component. At least one optical component of each group is provided with a dielectric layer capable of preventing propagation of a backreflected light toward laser diodes at a wavelength different from the pump wavelength.

Abstract: A portable laser head has a single-piece holder configured with a plurality of spaced-apart nests. The nests are arranged to receive at least a non-linear frequency converter, a V-shaped beam splitter and a dump collimator. Alternatively, the holder has multiple nests configured to receive an input collimator and output focusing optics unit in addition to the non-linear frequency converter, V-shaped beam splitter and dump collimator. The holder is characterized by small dimensions allowing for self-alignment of the above-referred components.

Abstract: A laser assembly is configured with a frequency conversion laser head operative to shift a fundamental frequency of input light to the desired frequency of an output light. The frequency conversion laser head includes a dump means operative to guide an unconverted output light at the fundamental frequency outside the case of the frequency conversion laser head. The dump means is configured with a guide optics operative to couple the output light at the fundamental frequency to a fiber terminating outside the case of the frequency conversion laser head.

Abstract: A powerful fiber laser system is configured with at least one large-area multi-clad rare-earth doped fiber, which is configured with a MM core capable of propagating a single mode laser emission at a first wavelength, and with at least one pumping assembly capable of generating an optical pump output at a wavelength shorter than the first wavelength of the rare-earth doped fiber. The pumping assembly has a plurality SM fiber lasers coupled to a SM-MM combiner which is operative to lunch the pump output into the cladding of the rare-earth doped fiber so that the powerful fiber laser system is operative to deliver a power of up to 20 kW.

Abstract: A waveguide receiving light which propagates through free space is configured with a coupler and delivery fiber. The coupler, including a GREEN or multimode fiber, has a protective coating and so does the delivery fiber. Upon splicing of the coupler to the delivery fiber, the protective coatings of the respective coupler and delivery fiber are spaced apart exposing thus end regions of the respective coupler and fiber. The exposed regions are covered by a light stripper made of material having a refractive index which is substantially the same as or greater than that one of outer claddings. Accordingly, the light stripper minimizes the amount of light capable of coupling into the protective coatings of the respective delivery and coupler fibers enhancing thus a power handling capabilities of the waveguide.

Abstract: A wavelength division multiplexing (WDM) fiber optic communication system is operative to transmit WDM signals between multiple nodes. Each of the nodes has a booster EDFA, and in-band (IB) and out-of-band (OB) supervisory channels operative to monitor the integrity of a transmission link by generating and detecting respective in-band and out-of-band control signals. The booster EDFA is operative to receive the multiplexed WDM and IB signals and generate an output signal carried by a plurality of fiber-optic cables between the nodes. The booster EDFA is operative to switch from an automatic gain control regime upon detecting of at least one of the IB and OB signals to an automatic power control regime upon loss of both IB and OB signals. The output signal of the EDFA in the AGC regime has a high power sufficient for being transmitted the WDM and IB signals, and has a low power in the APC regime sufficient for transmitting only the IB signal between the nodes.

Abstract: An epoxy-free collimator assembly is configured with a ferrule and a lens operative to move within an outer case to a desired position therebetween. The collimator assembly further has an aligning component made from soft, malleable material which is capable of filling out the radial space between the ferrule and case so as to spatially fix the aligned fiber held in the ferrule and lens in the desirable position.

Abstract: Apparatus and method for equalizing a multiplicity of amplifier optical output signals comprised of a combined broadcast optical signal and a narrowcast optical signal having different bands of wavelengths of light by adjusting the power output level of at least one the signals in response to an amplified sample of the signal. A light switch or attenuator and a sensor for determining whether a transmission fiber is in place is connected to each of the multiplicity of optical output signals to allow the optical output signals to be turned on and off for maintenance and repair.

Abstract: A single-mode fiber laser includes a single mode holding, large mode area optical fiber assembly having a large mode area core, a first cladding and a second cladding. The optical fiber assembly has several unique sections including a gain section having a ytterbium-doped core, first and second reflective sections including fiber Bragg gratings that define a lasing cavity, and an absorptive section also having a ytterbium-doped core, the absorptive section having an output end coupled to an input end of said first reflective section. A broad area, multi-mode diode pump source is configured to pump multi-mode light into a tapered input section and cladding-pump the gain section. The gain section absorbs the multi-mode pump light and emits single-mode light. The absorptive section absorbs emissions at the operating wavelength and prevents operating emissions from reflecting back into said pump source.

Abstract: A large mode area optical fiber includes a large diameter core (d1 up to 60 ?m), and a first cladding (diameter d2) wherein the difference between refractive index (n1) in the core and the first cladding (n2) is very small (?n<0.002), thus providing a very low numerical aperture core (NA1 between 0.02 and 0.06). The preferred ratio of d2/d1<2. The fiber further has a second cladding, preferably a layer of air holes, having a very low refractive index n3 as compared to the core and first cladding such that the first cladding has a relatively high numerical aperture (NA2>0.4) (n3 is preferably less than 1.3). The small change in refractive index between the core and inner cladding combined with a large change in refractive index between the first cladding and second cladding provides a significantly improved single mode holding waveguide.

Abstract: A low temperature fluorophosphate glass useful for joining single-mode fluoride and silica optical fibers includes 5 to 7 mol % InF3, 20 to 35 mol % PbF2 and 57.5 to 75 mol % P2O5. An alkali for maintaining a low glass transition temperature can be included. Up to 25% (glass molar basis) of the P2O5 can be replaced by PbO.